Apparatus for the control of highway crossing signals



Sept. 3, 1946. 2,406,955

APPARATUS FOR THE CONTROL 0F HIGHWAY CROSSING SIGNALS v Filed Dec. 15, 1944 Patented Sept. 3, 1946 APPARATUS FOR THE CONTROL O HIGHWAY CROSSING SIGNALS Carl F. Lower, Edgewood, Pa., assignor to The Union Switch & Signal Company, Swissvale,- Pa., a corporation of Pennsylvania.

n Application December 15, 1944, Serial No. 568,288

My invention relates to apparatus for the control of highway crossing signals, and more particularly to apparatus for controlling operation of the highway crossing signal in accordance with the speed of the train.

A highway crossing signal is frequently con-V trolled through a time measuring means `which is Agoverned by the track circuit of .an approach time measuring section. The control of the signal is such that operation of the signal is delayed When the time measuring means has been operated for its predeterminedinterval indicating the train speed lto be less than the preselected value. In `such a control system ya failure of the track circuit of .the time measuring section may cause operation of the time measuring means and a delay in ithe operation of the highway crossing' signal lto be falsely introduced when a train next approaches the intersection unless additional apparatus is provided. Such a track circuit failure may therefore result in a dangerous condition for highway users.

Accordingly, a feature of my invention is the provision of novel and improved apparatus for control of highway crossing signals according to the speed of the train.

Another feature of my invention is tha provision of highway crossing signal control apparatus incorporating novel means to check 'the track circuit of the time measuring section.

An additional feature of my invention is the provision of novel and improved apparatus controlled -by a train as it travels through two or more consecutive track sections in the approach of a highway crossing to initiate the operation of .a highway .crossing signal when the train exceeds the limit of speed preselected for each section.

Other features, objects and advantages of my invention will appear as the specification progresses. K

The above: features, objects and advantages of my invention are obtained by forming the track on the approach side of a highway crossing into a series of consecutive sections, each of which is provided with a track circuit. The number of such sections is predetermined according .to the maximum permissible speed for all trains, and according to the .permissible variations in the warning period of the signal. The section most remote' from the intersection 'is used asa time measuring section, sections nearer tol the intersection areused bothas a time' measuring sectionand as an operating section, and the section adjacent the intersection is made a ipositive operating section.

5 claims. `(o1. 24e- 130) A separate time measuring means is preferably associated with each time measuring section, and each such means is adjusted for an operation periodlwh'ich is preselected to agree with the time consumed yby the train in traveling the associated section at a predetermined speed. Each of the time measuring means is effectively energized for operation thereof through `a circuit including a back contact of the track relay of the associated section so that each time measuring means is operated While a train is moving through that section. If a time measuring means completes its movement indicating .that a train is traveling at ya speed below the speed limit prescribed for the respective section, the warning operation of the signal is heldin abeyance while the train occupies the section next toward the intersection. In this way .the point at which the warning operation of the signal is started is dependent upon the speed of the train.

To check the .track-circuits so that a release of .a track relay While the associated track section is unoccupied cannot cause an cperationof the time measuring means associated with that sec'- tion and falsely introduce a delay period in the initiating of the warning signal for the next apy proaching train, I provide a checking group'of three relays. A rst one `of this group of relays is normally energized' through a back contact of a third one of the relays, and a front contact of the track relays of each of the sections except .the first measuring section. A second one of the group of relays is a slow release relay which is i approach controlled by a train approaching the measuring section. The third relay is a stick relay having a pick-up circuit which includes a back contact of the track relay of the measuring section and a front contact of each of the first and second relays. The stick circuit for this third relay includes its own front -contact and a front contact of the track relay for the section adjacent the intersection. Front contacts of the third relay are used inturn to control the operation of each of the time measuring means, and thus each time measuring means can be energized only when the track circuits are all normal and a train approaches through the measuring section. Also, afailure of .a track circuit ahead of .the train serves to deenergizethe time measuring means :an-d to immediately initiate operation of the highway crossing signal. In this way a time measuring means cannot 'be operated to falsely introduce a delay periodin the operation of a highW-ay'crossing signal due to release of -atrack 3 relay while the associated track section is unoccupied.

I shall describe one form of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view showing one form of apparatus embodying my invention.

Referring to the drawing, the reference characters la and Ib designate the track rails of a moves in the direction indicated by an arrow and which track is intersected by a highway H. The rails on the approach side of the highway are formed by the usual insulated rail joints with a series of consecutive track sections IT, 2T, 3T, 4T and AT, and which track sections a train traverses in the order reverse to that named as it approaches the highway. Each of these track sections is provided with a track circuit including a source of current such as, for example, a battery TB connected across the rails at one end of the section and a track relay designated TR, plus a numeral or letter corresponding to that of the section connected across the rails at the other end of the section. These track sections are made of predetermined lengths which are made to agree with the maximum permissible speed for all trains and with the-warning period of the highway crossing signal.

To aid in the understanding of the invention, 1 shall assume that the maximum permissible speed for all trains is 90 miles per hour and that a minimum warning period of twenty seconds prior to the arrival of a train at the intersection for the highway crossing signal is required. Under such circumstances, the section IT may be 880 feet in length and form a to 30 miles per hour zone because a train operating at 30 miles per hour travels 880 feet in seconds. For train speeds less than miles per hour the warning period of the signal would be correspondingly higher. Section 2T may also be 880 feet in length and the two sections IT and 2T may be considered as a 30 to 6() miles per hour zone. That is, the combined length of the sections IT and 2T is 1760 feet to provide 20 seconds warning period of the signal for a train traveling at 60 miles per hour. For trains traveling at a speed between 30 and 60 miles per hour, the warning period of the highway crossing signal would be correspondingly increased but would not exceed seconds. Likewise, the section 3T may be 880 feet in length and the three sections IT, 2T and 3T serve as a to 90 miles per hour zone, because the combined length of the three sections is 2640 feet and they provide 20 seconds warning period for a train moving 90 miles per hour. Section 4T is a measuring section and it may be of any suitable length and by way of illustration I shall assume it is 880 feet in length. The length of section AT is immaterial, the track relay of this section being used as an approach control device. As will appear hereinafter, the section IT is a positive operating section, and the operation of the signal is eifected when a train occupies this section whether the train is moving or not. Section 2T is an operating section, and section 3T is a section used both as a measuring section-and as an operating section. Section 4T as stated above is a measuring section.

It is to be understood, of course, that my in vention is not limited to this one arrangement of track sections and a larger or a smaller number of sections may be used and the sections may be l0 stretch of track over which traic normallyV 4 of different lengths, the length of the sections being made to suit the train speeds and. the warning period of the signal at the particular location.

A highway crossing signal S is located at the intersection, and this signal may be any one or a combination of the several types of such signals, and as here shown it is an audible signal in the form of an electric bell. The immediate control of signal S is effected through a signal control relay EXR, the arrangement being such that when relay EXR is energized the bell S is silent, but that when the relay EXR is deencrgized and released to close back contact EB an obvious cir cuit is completed and the bell is energized to sound a warning.

Control relay EXR is governed through a line circuit having three alternative paths. The rst one of these paths is that by which the relay is and 2G attached thereto.

normally energized and extends from terminal B of a convenient source of current, such as a battery not shown, through front contact il of track relay STR, front contact I2 of track relay ZTR, checking contact I3 of a relay IETR, to be referred to shortly, front contact Il. of track relay ITR, checking contact I5 of a relay ZETR, also to be referred to shortly, and winding of relay EXR to terminal C of the source of current. A second path includes terminal B, front contact I6 of track relay ZTR, front contact I'l of relay IETR, wire I, front contact I?. of relay ITR and as previously traced for the rst path. A third path includes terminal B, front contact I9 of relay ITR, front contact 29 of relay ZETR, wire 2l and winding of relay EXR to terminal C. It follows that when sections IT, 2T and 3T are unoccupied and each of the relays IETR and 2ETR is set at an initial position, the control relay EXR is energized. Also, when section 3T is occupied to shunt track relay STR and the sections 2T and IT arenot occupied, relay EXE. is energized pro viding the relay IETR is operated to close the l contact II and complete the second branch path of the control circuit. Again, when section 2T is occupied to shunt track relay ZTR, the control relay EXR. is energized through the third path of the control circuit providing the relay ZETR is operated to close contact 29. If section IT is occupied to shunt track relay lTR. relay EXR is deenergized.

Relays IETR and ZETR are time element relays. They are preferably alike in construction and may be any one of several types. Their construction may be, for example, similar to that disclosed in Letters Patent of the United States No. 1,966,965, granted July 17, 1934, to Branko Lazich and Harry E. Ashworth, for Electric relays, except as the structure is modied to respond to recurrent or time spaced impulses. It

. is suflicient for this application to point out that relay IETR, for example, is provided with a clutch or holding winding 22, an operating winding 23 and a ratchet operated armature having three circuit controlle;` contact members 24, 25 The arrangement is such that when clutch winding 22 is deenergized, the armature falls by its own weight or by a bias to an initial position, that is, to the position where the contact members 24, 25 and 1216 occupy the positions illustrated in the drawing. In this initial position, the contact member 25 engages contact I3 to check the initial position of the armature, When clutch winding 22 is energized, and the operating winding 23 is supplied with time spaced impulses, the armature is operated in a step by step movement away from the initial position to an extreme or operated position. In this movement contact member 25 disengages contact I3 immediately after the armature leaves the initial position and the contact members 24 and 26 engage contacts I1 and 21, respectively, only at the extreme position. The number of impulses required to complete such a movement is predetermined by an adjustment of the relay, Thus with impulses of a preselected frequency or code rate, the operating time of the relay can be preselected. For example, if the impulses are of a rate of 75 impulses per minute and the relay is adjusted to require 8 impulses to complete its movement, the contact members 24 and 26 engage their respective contacts I1 and 21 in 10 seconds, this being the operating time indicated in the drawing. The connection for the operating winding 23 is opened at the extreme position to discontinue further movement of the armature and if the clutch or holding winding 22 remains energized the armature is retained at.

this extreme position. It is to be noted that encrgization of the operating winding 23 without energization of the clutch winding 22 is ineffective to operate the relay. Also, the armature is restored immediately to the initial position from any intermediate position in the event the clutch winding :22 becomes deenergized.

The time element relay 2ETR is similar to relay I ETR but it is adjusted to operate its contact members 2S and 25 to close contacts 23 and 33, respectively, in response to 16 impulses of a 3'15 code rate, that is, it closes the contacts in 20 seconds. Contact member 3| of the relay ZE'IR engages contact I5 to check the initial position of the relay.

Code impulses are supplied to the operating windings 23 and 34 of the Vtwo time element relays through a continuously operating code transmitter CT which is operated to close its contact 32 at the code rate of 75 times per minute. The circuit through which such code impulses are supplied extends from terminal B of the source of current through contact 32 of coder CT, wire 33, and the two operating windings 23 and 34 in multiple to terminal C of the current source.

The clutch winding22 of relay IETR is controlled by a line circuit having two alternative paths. A rst circuit path extends from terminal B through' back contact 35 of track relay 4TRof the time measuring section 4T, front contact 36 of a relay 5, to be referred to later, front contact 31 of track relay STR. and winding 22 of relay IETR to terminal C. The second path includes terminal B, front contact 21 of relay IETR, iront contact n38 of track relay 2TR and winding 22 to terminal C, It is to be seen, therefore, that when a train occupies the measuring section 4T to `shunt the relay 4TH, closing back contact 35,V relay 5 is picked up in a manner to shortly appear to close front contact 36, and section 3T is unoccupied so that track relay 3TH. is picked up closing front contact 31, the time element IETR isoperated from its initial position toward its extreme position. If a train moves through the section 4T at a speedabove 60miles per hour and consumes less than seconds in passing through the section and entering section 3T to shunt track relay 3TR, the time element relay IETR is deenergized causing its armature to fall back from whatever position it had been advanced to the initial position. IfV the train is moving at less than 60 miles per hour and consumes more than 10 'seconds in moving through thesection '4T so that the contact member 26 engages contact 21 to complete the second path for winding 22, the relay is retained energized atits Vextreme position after the train enters the sectionV 3T and remains at its eXtreme position until the train` enters the section- 2T and shunts the track relay 2TR.

Similarly, the clutch winding 42 of time element ZETR is controlled through a line circuit having two branch paths, a rst one of which extends from terminal B through front contact 39 of relay 5, back contact 4I! oi track relay 3TR, front contact 4I of track relay 2TR. and clutch winding 42 to terminal C; and a second one of which paths includes terminal B, contact 3U of relay ZETR, iront contact 43 of track relay ITR, winding 42 and terminal C. It follows that when relay 5 is picked up closing front contact 33 and `a train occupied section 3T to shunt track relay 3TR closing hack contact 40, vthe time element relay 2ETR. is operated from its initial position toward its extreme position. Ii the train is traveling at less than 30 miles per hour so that it consumes something over 20 seconds in moving through section 3T, the time element relay 2ETR is operated to its extreme position closing contact 36 and the relayis retained energized at its extreme position while the train travels the section 2T. If the train is moving through section 3T at a speed above 30 miles per hour and consumesless than 20 seconds, then the time element relay ZETR is reset to its initial position when the train enters the section 2T. The two time element relays IETR and IZETR control alternative paths in the line circuit for the control relay EXR in the manner explained hereinbefore.

The means to check the track circuit includes a group of check relays 5, l and 1. Relay 6 is normally energized through a line circuit that includes front contacts 45, 45 and 41 of track relays ITR, ZTR and 3TH., respectively, and back contact 48 of relay 54. Relay 1 is a slow release relay. which is approach controlled through a circuit including back contact di! of track relay ATR of the section AT next in. the rear of the measuring section 4T and front contact 53 oi track relay 4TR of the measuring section. Relay 5is a stick relay provided with a pick-up circuit including terminal B. hack contact 49 of relay ATR, back contact 5| of track relay ATR, front contact 52 of relay 1, front contact 53 of relay 6, winding of relay 5 and terminal The stick circuit includes terminal B, front Contact 54 of track relay ITR, front contact 55 and winding of relay 5 and terminal C.

It is to be seen, therefore, that relay 6 is energized only if the track circuits of sections IT, 2T and 3T are all normal to pick up their respective track relays and the stick relay 5 is released, The slow release relay 1 is picked up when a train approaches if the track relay cf the measuring section is picked up, and the third or stick relay 5 is picked up when the train enters the measuring section only if the two relays 6 and 1 are picked up, the pick-up circuit for relay 5 being closed during the slow release period of relay 1. The stick relay 5 once picked up is retained energized while the train advances toward the highway until the train enters the iinal section IT adjacent the highway, and the stick relay 5 controls the energizing circuits of the clutch windings of the time element relays. If any one of the track circuits of section IT, 2T and 3T' fails,V the first relay 6 of the group of relays is deenergized and the stick relay cannot be picked up to prepare the circuits of the time element relays when a train enters the time measuring section. Also if the track circuit for the measuring section 4T fails, the slow release relay 'I is not picked up by the approach of the train and relay 5 remains deenergized and the time element relays are not operated. Thus a failure of any of the track circuits of the several sections or a broken line wire cannot operate a time element relay to falsely establish a delay period for the highway crossing signal When a train next approaches the intersection.

Assuming the apparatus to be normal, that is in the position illustrated in the drawing, and a train moving at 90 miles per hour approaches the intersection, the relay 1 is picked up while the train occupies the section AT and relay 5 is energized during the slow release period of relay 1 when the train enters the section 4T. Time element relay IETR is operated while this train moves through the measuring section 4T, but since the train consumes only a little over 6 seconds in moving through section 4T, the relay dETR does not complete its movement and is deenergized and restored to its initial position when the train enters the section 3T. When the train shunts the track relay 3TH, to close back contact 4i), the second time element relay ZETR is operated but since this train will consume only about 6 seconds in moving through the track section 3T, the relay ZETR is deenergized and restored to its initial position when the train enters the section 2T to shunt track relay 2TR.

When the track relay 3TH was released to open front contact ll in response to the train entering section 3T, the control relay EXRl is deenergized and initiates the warning operation of the highway crossing signal S because neither one of the two alternative paths for the relay EXR is closed by the time element relays. Consequently, for this train traveling at 90 miles per hour, the signal S is operated while the train is moving through the three sections 3T, 2T and IT and a 20 seconds Warning period is eiected.

Assuming a train traveling at a speed just under 60 miles per hour approaches the intersection, the train consumes slightly over seconds in traveling the measuring section 4T and the rst time element relay IETR completes its operation and is retained at its extreme position through the branch path including its own contact 26 when the train enters the section 3T. With relay IETR. held at its extreme position, the control relay EXR is retained energized by the branch path through contact l1 of relay IETR, while the train occupies the section 3T. The second time element relay ZETR is set into operation when the train enters section 3T to shunt track relay STR and close back contact 40. This train will consume only a little over 10 seconds in advancing through section 3T, and relay ZE'IR whose operating period is 20 seconds is deenergized and restored to its initial position when the train enters section 2T to shunt relay ZTR.. The release of relay ZTR opening front contact 2l causes relay IETR to be deenergized and restored to its initial position and in turn causes the control relay EXR to be released to start the warning period of the highway crossing signal S. Signal S is thus operated while this train advances through sections 2T and IT and a warning period of substantially seconds is provided.

Assuming a train traveling just under 30 miles per'hour approaches, this train consumes a little over 20 seconds in advancing through the measuring section 4T and the time element relay IETR is operated to its extreme position to close contact 21 so that it is retained energized while the train is in section 3T. The relay IE'IR in turn closes the second path of the line circuit, and relay EXR is retained energized. The second time element relayv ZETR is operated to close its contact 3D While this train advances through the section 3T since the train will consume a little over 20 seconds in traveling the section 3T. Relay ZETR then is retained at its extreme position when the train is in section 2T with the result the control relay EXR is held energized while the train is in section 2T. When this train enters section IT to shunt track relay II'R, relay ZETR and the control relay EXR are deenergized, the release of the control relay causing the warning operation of the highway crossing signal. This train moving at little less than 30 miles per hour will consume slightly over 20 seconds in advancing through section IT to the intersection, and hence the warning period of the signal is substantially 20 seconds.

Operation of the apparatus for a train traveling at any other speed other than that explained hereinbefore will be apparent by an inspection of the drawing taken in connection with the description of the operation of the apparatus for train speeds of 90, 60 and 30 miles per hour.

It is apparent that the track circuit checking means, that is, the group of relays 5, 6, and 1, together with their respective circuits can be used with time measuring means other than that shown in the drawing and also when the track circuits and track sections are arranged for more or less number of track sections.

Although I have herein shown and described but one form of apparatus for the control of highway crossing signals embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a speed measuring track section provided with a track circuit having a normally energized track relay, a signal controlling electroresponsive time measuring means, a line circuit including a back contact of said track relay to energize said time measuring means to measure the time consumed by a train in traveling said section, a first traic controlled contact closed in response to a train approaching said section, a second traic controlled contact which becomes open When a train passes beyond said section, a nrst relay energized through said second contact, a slow release relay energized through said nrst Contact and a front contact of said track relay, a stick relay having a pick-up circuit including a back contact of said track relay and a front contact of each of said rst relay and said slow release relay, a stick circuit for said stick relay, and a front contact of said stick relay interposed in said line circuit to avoid energizing said time measuring means due to a failure of said track circuit.

2. In combination, a speed measuring track section provided with a track circuit having a normally energized track relay, a signal controlling electroresponsive time measuring means, a line circuit including a back contact of said track relay to energize said time measuring means to measure the time consumed by a train in traveling said section, an approach track relay shunted in response to a train approaching said section, another track relay shunted in response to a train passing beyond the section; a group of checking relays comprising a first, a slow release and a stick relay; said iirst relay energized through a front contact of said other track relay, said slow release relay energized through a back contact of said approach track relay and a front contact of the track relay of said section, a pick-up circuit for said stick relay and including a back contact of the track relay of said section and a front contact of each of said iirst relay and said slow release relay, a stick circuit for said stick relay and including a front contact of said other track relay, and a front contact of said stick relay interposed in said line circuit to avoid energizing said time measuring means due to a failure of said track circuit.

3. In combination, a speed measuring track section provided with a track circuit having a normally energized track relay, a time element relay having a signal controlling contact which becomes closed when the relay is effectively energized for a preselected time interval, a line circuit. including a back contact of said track relay to energize said time element relay to close said signal controlling contact when a train consumes said time interval in traveling through said section; a first, a slow release and a stick relay; means including a back contact of said stick relay and a normally closed contact which a train opens when it has passed beyond said section to energize said rst relay, means including a iront contact of the track relay of said section and a contact which a train closes in approaching the section to energize said slow release relay, a pickup circuit including a back contact of the track relay of said section and a front contact of each of said first` and said slow release relays to energize said stick relay, a stick circuit to energize said stick relay, and a front contact of said stick relay interposed in said line circuit to avoid energizing said time element relay due to a failure of said track circuit.

4. In combination, a speed measuring track section provided with a track circuit having a normally energized track relay, a signal controlling electroresponsive time measuring means, a line circuit including a back contact of said track relay to energize said time measuring means to measure the time consumed by a train in travcling said section, an approach track relay shunted in response to a train approaching said section, another track relay shunted in response toa ftrain passing beyond the section; a group of checking relays comprising a rst, a slow release and a stick relay; means including a back contact of said stick relay to energize said iirst relay, means including a back contact of said approach track relay and a front contact of the track relay of said section to energize said slow release relay, a pick-up circuit including a back contact of the track relay of said section and a front contact of each of said first and said slow release relays to energize said stick relay, a stick circuit for said stick relay including its own front contact and a front contact of said other track relay, and a front contact of said stick relay interposed in said line circuit to avoid energizing said time measuring means due to a failure oi said track circuit.

5. In combination, a stretch of railway track interseclted vby a highway, said track formed with a measuring and a first and a second operating section which a train travels in the order named when approaching the intersection, a track circuit including a normally energized track relay for each of said sections, a time element relay having a normally open contact which becomes closed when |,the relay is energized a predetermined time interval, a rst line circuit including a back contact of the track relay of said measuring section to energize said time element relay, a highway crossing signal at said intersection, a control relay to govern the operation of said signal, a second line circuit including a front contact of the track relay of each of said rst and second operating sections to govern said control relay, means including said time element relay contact to render said front contact of said track relay of said first operating section ineffective to govern said second line circuit; checking means including a first, a slow release and a stick relay; means including a back contact of said stick relay to energize said first relay, means including a iront contact of @the track relay of said measuring section and a contact controlled by a train approaching said measuring section to energize said slow release relay, a pick-up circuit including a back contact of the track relay of said measuring section and a front contact of each of said first and said slow release relays to energize said stick relay, a stick circuit including a front contact of the track relay of said second operating section to energize said stick relay, and a front contact of said stick relay interposed in said rst line circuit.

' CARL F. LOWER. 

